Device and method for parallel pressure-volume-temperature analysis using gas chromatography and mass spectrometry

ABSTRACT

A device and method is described to parallelize a pressure-volume-temperature (“PVT”) analysis using gas chromatography and mass spectrometry techniques such that a portion of the pressure, temperature and volume analysis is performed separately from others. The resulting PVT data is then recombined statistically for a complete PVT analysis. The device may also obtain compositional data of the fluid to perform an equation of state analysis or reservoir simulations.

PRIORITY

This application is a continuation of U.S. patent application Ser. No.14/772,261 filed Sep. 2, 2015 and entitled “DEVICE AND METHOD FORPARALLEL MICROFLUIDIC PRESSURE-VOLUME-TEMPERATURE ANALYSIS,” which is aU.S. National Stage patent application of International PatentApplication No. PCT/US2013/037227, filed on Apr. 18, 2013 bearing thesame title, the benefits of which are claimed and the disclosures ofwhich are incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The present invention generally relates to pressure-volume-temperature(“PVT”) analysis of fluids and, more particularly, to a microfluidicdevice and method to parallelize a PVT analysis such that a portion ofthe pressure, temperature and volume analysis is performed separatelyfrom others, thereby rapidly increasing the overall analysis time.

BACKGROUND

In the oil and gas industry, PVT experimentation is utilized todetermine the phase behavior of reservoir fluids under variouspressures, volumes, and temperatures. Such information is useful inderiving the economic value of a play, designing production strategiesand managing production over the lifetime of an asset. PVT propertiesmust be discovered to effectively manage an asset or collection ofassets, including pipeline shipping.

Conventional PVT analysis, however, suffers from at least two drawbacks.First, the size of conventional PVT devices is too large forspace-sensitive applications, such as downhole environments. Second, thetime required to conduct conventional PVT experiments is too lengthy. Afull PVT analysis usually takes days for a basic test to weeks for fulltesting. Particularly, it has taken months for some specialized PVTtesting. Therefore, conventional PVT analysis has been limited downholeto a few simple rapid PVT-determined properties at a single or limitedpressures-temperature combinations close to wellbore conditions (whichmay not exactly match reservoir conditions).

Accordingly, in view of the these drawbacks, there is a need in the artfor a compact and versatile PVT analysis device which provides accuratedata in a rapid fashion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a microfluidic device according to an exemplaryembodiment of the present invention;

FIGS. 2A and 2B illustrate arrangements for a nuclear magnetic resonanceapparatus and a compositional analysis apparatus of the microfluidicdevice, according to alternative exemplary embodiments of the presentinvention;

FIG. 2C illustrates a chromatographic column utilized as a microfluidicchannel according to an exemplary embodiment of the present invention;

FIGS. 3 and 4 illustrate alternative arrangements for an NMR apparatusutilized within a microfluidic device according to certain exemplaryembodiments of the present invention; and

FIGS. 5 and 6 are flow charts of alternate methodologies for performinga PVT analysis, is in accordance with certain exemplary methodologies ofthe present invention.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Illustrative embodiments and related methodologies of the presentinvention are described below as they might be employed in amicrofluidic device and method to parallelize a PVT analysis. In theinterest of clarity, not all features of an actual implementation ormethodology are described in this specification. In addition, the“exemplary” embodiments described herein refer to examples of thedisclosed invention. It will of course be appreciated that in thedevelopment of any such actual embodiment, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which will vary from one implementation toanother. Moreover, it will be appreciated that such a development effortmight be complex and time-consuming, but would nevertheless be a routineundertaking for those of ordinary skill in the art having the benefit ofthis disclosure. Further aspects and advantages of the variousembodiments and related methodologies of the invention will becomeapparent from consideration of the following description and drawings.

As described herein, the present invention is directed to a microfluidicmethod and device to parallelize a PVT analysis such that part of apressure, temperature and volume combination is performed separatelyfrom others, thus providing a rapid PVT analysis. In one exemplaryembodiment, a microfluidic cell, or chip, is designed to accept a smallamount of fluid, separate the fluid into a number of sample volumes, anddistribute the sample volumes to a plurality of parallel microfluidicchannels (or columns). A nuclear magnetic resonance (“NMR”) apparatus isthen utilized to determine the phase characteristics (amount of liquid,gas or solid) of the fluid sample volumes within in each microfluidicchannel. The same or differing pressure, volume or temperature may beutilized in multiple microfluidic channels. Circuitry on-board, orremote from, the microfluidic device then utilizes the phasecharacteristic data to perform a variety of PVT experiments to derivephase behavior, transport property, bulk property, etc. In otherexemplary embodiments, the phase characteristic data of each channelrepresenting multiple pressure, temperature and volume pointmeasurements is recombined statistically across PVT space with orwithout PVT point repeats for a complete PVT analysis, thus improvingthe is accuracy over the repeated experiments occurring in the channels.

Accordingly, by dividing the fluid into a plurality of separatechannels, the PVT analysis time is greatly reduced. If, for example, acomplete prior art PVT analysis required 3 hours, by dividing that samefluid volume into 65 parallel channels using the present invention, theanalysis time could be reduced to less than 3 minutes. Since any numberof microfluidic channels and/or chips may be utilized at once, thepresent invention also provides redundancy and robustness.

As further described herein, exemplary embodiments of the device mayalso include a compositional analysis apparatus that determinescompositional characteristics (C1-C4 hydrocarbons, etc.) of the fluidsample volumes within the channels. The compositional analysis apparatusmay be, for example, a chromatographic, optical or NMR apparatus. Insuch embodiments, the microfluidic devices perform an Equation of State(“EOS”) analysis of the fluid sample and/or performs a reservoirsimulation based upon the phase and compositional characteristic data.These and other advantages of the present invention will be apparent tothose ordinarily skilled in the art having the benefit of thisdisclosure.

FIG. 1 illustrates a microfluidic device 100 for performing a PVTanalysis of a fluid in accordance with certain exemplary embodiments ofthe present invention. As will be understood by those ordinarily skilledin the art having the benefit of this disclosure, microfluidic cells aretypically micro-sized chips that handle the flow of small amounts offluid through chambers and canals via an intricate valving and pumpingsystem, much like how computer chips handle the flow of electronsthrough circuits and transistors. The semiconductor material along thechip may be constricted or otherwise manipulated via application ofelectrical signals to affect pumping or the opening/closing of valves.However, there are a variety of other techniques and materials utilizedin the fabrication and design of microfluidic devices, all of which areconsidered to be within the scope of the present invention.

In this exemplary embodiment, microfluidic device 100 includes inletport 12 for receiving a fluid sample 14. Fluid sample 14 may be anyfluid (liquid or gas) or fluid containing a solid substance or materialsuch as, for example, rock formations, slurries, sands, muds, etc. Inthe exemplary embodiments described herein, however, fluid sample 14 isa multiphase wellbore fluid (comprising oil, gas, water, solids, forexample) consisting of a variety of phase characteristics (i.e., liquid,gas and solid phases) and compositional characteristics such as, forexample, C1, C2, C3, C4 and higher hydrocarbons, inorganic gases,groupings of such elements, and saline water. Fluid sample 14 may beprovided to microfluidic device 100 in a variety of ways including, forexample, through a flow pipe or sample cell containing fluid sample 14.

Microfluidic device 100 includes a plurality of microfluidic channels 16a-k in fluid communication with inlet port 14 to receive a volume of thefluid sample 14. Microfluidic channels 16 a-k are parallel to oneanother such that each inlet of channels 16 a-k is in fluidcommunication with inlet port 12 to thereby receive a volume of fluidsample 14. A plurality of valves 18 are positioned throughoutmicrofluidic device 100 to affect movement and isolation of fluidthroughout the device, in addition to manipulation of the walls ofmicrofluidic channels 16 a-k (to affect volume). Valves 18 include inletvalves 18 a and outlet valves 18 b which allow the flow of fluid intoand out of channels 16 a-k, respectively. Although not illustrated forsimplicity, microfluidic device 100 may also comprise any number ofadditional valves, reservoirs, pumps, mixers, etc., necessary to performdevice functions, such as volume expansion. For example, semi-permeablemembranes may be used to draw specific phases from the fluid samplevolume as, for example, gas in a differential liberation PVT experiment.Also, the pressure of the exterior of the chip may be increased ordecreased to ease the restrictions on components such as valves orvolume constrictions. In certain other exemplary embodiments,microfluidic channels 18 may comprise a number of additional valvespositioned there along so that the volume of fluid injected intomicrofluidic channels 18 may be altered as desired.

As fluid sample 14 flows into inlet port 12, one or more inlet valves 18a are opened while valves 18 b remain closed to allow fluid to flowinto, and be contained by, microfluidic channels 16 a-k. Fluid may beallowed to flow into one, a subset of, or each microfluidic channel 16a-k. In this exemplary embodiment, an NMR apparatus 20 is positionedadjacent to one or more of microfluidic channels 16 a-k in order togenerate a magnetic field across the sample volume of fluid contained inthe channel. As will be understood by those ordinarily skilled in theart having the benefit of this disclosure, NMR apparatus 20 exposes thefluid sample volumes to a magnetic field and resonant frequency pulsesto determine the amount of liquid, gas or solid material (i.e., phasecharacteristics) within the sample volumes at a given pressure andtemperature. The is operation of NMR is well known in the art and willnot be described in detail herein. NMR apparatus 20 then generates asignal corresponding to each phase characteristic measurement along eachmicrofluidic channel 16 a-k.

In certain exemplary embodiments, NMR apparatus 20 applies a homogenousmagnetic field across one, a subset of, or each microfluidic channel 16a-k. As will be understood by those ordinarily skilled in the art havingthe benefit of this disclosure, a homogeneous field is essential tospectroscopy measurements and enables better separation of NMR frequencycharacteristics associated with different fluid molecules. In addition,a homogeneous field produces a narrow line width making thefree-induction-decay signal last longer, thereby providing a strongersignal. In yet other embodiments, NMR apparatus 20 applies a gradientmagnetic field across one, a subset of, or each microfluidic channel 16a-k. A gradient field is useful for distinguishing fluid molecules basedon their corresponding diffusion characteristics.

As also understood by those skilled persons described herein, the phasecharacteristics of each fluid sample volume will be dependent upon thepressure and temperature applied to each fluid sample volume. Althoughnot shown, in addition to receiver coils, each microfluidic channel 16a-k includes a transmitter coil to transmit the signals to devicecircuitry 24 (CPU, for example) for further processing. Such coils maybe mounted or fabricated on individual microfluidic channels 16 a-k, incertain embodiments.

Device circuitry may be located onboard microfluidic device 100 or atsome remote location. Device circuitry 24 comprises a signal processor(not shown), communications module (not shown) and other circuitrynecessary to achieve the objectives of the present invention, as will beunderstood by those ordinarily skilled in the art having the benefit ofthis disclosure. In addition, it will also be recognized that thesoftware instructions necessary to carry out the objectives of thepresent invention may be stored within storage located within devicecircuitry 24 or loaded into that storage from a CD-ROM or otherappropriate storage media via wired or wireless methods. Communicationslink 26 provides a medium of communication between device circuitry 24and microfluidic device 100. Communications link 26 may be a wired link,such as, for example, a wireline extending down into a wellbore or afiber optic cable. Alternatively, however, communications link 26 may bea wireless link, such as, for example, acoustic communication, mud-pulsetelemetry and like devices. Also, an electromagnetic device of suitablefrequency may be utilized for communication.

Device circuitry 24, via its signal processor, controls operation ofmicrofluidic device 100. Although not shown, microfluidic device 100comprises a transmitter and receiver (transceiver, for example) (notshown) that allows bi-directional communication over communications link26 in real time. In certain exemplary embodiments, microfluidic device100 will transmit all or a portion of the characteristic data to devicecircuitry 24 for further analysis. However, in other embodiments, suchanalysis is completely handled by microfluidic device 100 and theresulting data is then transmitted to device circuitry 24 for storage orsubsequent analysis.

In addition to various phases, each sample fluid volume also comprises avariety of chemical compositions. Such chemical compositions of thefluid sample volumes include, for example, the presence and quantity ofspecific inorganic gases such as, for example, CO₂ and H₂S, organicgases such as methane (C1), ethane (C2) and propane (C3) and salinewater, in addition to dissolved ions (Ba, Cl, Na, Fe, or Sr, forexample) or various other characteristics (p.H., density and specificgravity, viscosity, total dissolved solids, sand content, etc.). Thus,in an alternative embodiment, one or more compositional analysisapparatuses 22 may be positioned adjacent to one or more of microfluidicchannels 16 a-k to detect such compositional characteristics.Alternatively, compositional analysis apparatus 22 and NMR apparatus 20may be positioned around the same microfluidic channel 16. Although only11 microfluidic channels 16 a-k are illustrated, there may be hundredsmore, for example. Compositional techniques may be applied to the samechannel or different channels and statistically recombined.Nevertheless, once the compositional characteristics are detected,compositional analysis apparatus 22 generates a corresponding signal andtransmits it to device circuitry 24 for further processing.

In certain exemplary embodiments, each microfluidic channel 16 a-k maybe specifically optimized to detect different compositionalcharacteristics of the fluid sample volume in parallel. For example,microfluidic channel 16 c may be specifically optimized for detection ofC1-C5 hydrocarbons, while microfluidic channel 16 d is optimized forC4-C8 hydrocarbon detection by compositional analysis apparatus 22. Theanalyzer is optimized, however, since pressure temperature and volumemay play a role in the optimization the channel itself, and its valve orcomponent configuration provides degrees of freedom for optimizationwith respect to the is analyzer.

Compositional analysis apparatus 22 may be, for example, achromatographic, optical or NMR apparatus. Gas Chromatography coupledwith Mass Spectrometry (“GCMS”) is one such chromatographic techniquewhich identifies each component in a complex mixture such as oil, andcan provide for each the chemical nature, vapor pressure distributionand boiling point. In addition to MS, GCMS, other chromatographictechniques include, for example, size exclusion chromatography, ionchromatography Fourier transform ion cyclotron resonance massspectrometry or liquid chromatography. Moreover, wet chemistrytechniques, including indicator chemistry, can be used to determinecomposition. Those ordinarily skilled in the art having the benefit ofthis disclosure realize these and a variety of other such techniques maybe utilized with the present invention.

Exemplary optical apparatuses include, for example, those utilizingIntegrated Computational Elements (“ICE”), also known as a MultivariateOptical Elements (“MOE”). As understood in the art, an ICE is configuredto receive an input of electromagnetic radiation from a substance orsample of the substance and produce an output of electromagneticradiation from a processing element. Fundamentally, an ICE opticalapparatus utilizes ICE structures to perform calculations, as opposed tothe hardwired circuits of conventional electronic processors. Whenelectromagnetic radiation interacts with a substance, unique physicaland chemical information about the substance is encoded in theelectromagnetic radiation that is reflected from, transmitted through,or radiated from the sample. This information is often referred to asthe substance's spectral “fingerprint.” The ICE structure extracts thespectral fingerprints of multiple characteristics or analytes within asubstance and, using regression techniques, directly converts thatinformation into a detectable output regarding the overall properties ofa sample.

In addition, other optical apparatuses may utilize, for example, indexof refraction, scattering or atomic layer deposition techniques.However, those ordinarily skilled in the art having the benefit of thisdisclosure realize these and a variety of other such techniques may beutilized with the present invention.

There are a variety of other alterations which may be embodied in thecompositional apparatuses utilized in the present invention. Forexample, optogalvanic lamps, holocathode lamps, Q-Dots or HT gas lasersmay be utilized as the electromagnetic source of the optical apparatus.An ICE structure may generate characteristic information to an opticalmagnetometer acting as a pump or accept characteristic data from amagnetometer acting as a probe. In addition, an ICE structure may alsobe utilized as an optical pump.

As previously described, the fluid sample volumes may be heated orcooled during the PVT analysis. Thus, with reference to FIG. 1,microfluidic device 100 may also comprise one or more devices to heat orcool the fluid sample volumes within microfluidic channels 16 a-k. Suchdevices may include, for example, thermal electric heating/coolingdevices (resistive devices, for example), positioned adjacent to oraround microfluidic channels 16 a-k. In certain embodiments, devicecircuitry 24 may control operation and monitoring of the temperaturesalong each microfluidic channel 16 a-k.

FIG. 2A illustrates a view of microfluidic channel 16 a-k taken alongline 2A of FIG. 1 to further illustrate certain exemplary embodiments ofthe present invention. Here, NMR apparatus 20 and compositional analysisapparatus 22 (here, an optical apparatus) are positioned along a commonmicrofluidic channel 16 a-k in which a fluid sample volume 28 isenclosed. In this embodiment, as illustrated, NMR apparatus 20 generatesand emanates magnetic field 26 along an axis perpendicular to an axis inwhich optical apparatus 22 emanates electromagnetic radiation 30 acrossfluid sample volume 28. While FIG. 2A reflects a transmission modedesign in which the electromagnetic radiation passes through fluidsample volume 28, it is also contemplated herein to reflectelectromagnetic radiation off of fluid sample volume 28 using areflectance or fluorescence mode design as illustrated in FIG. 2B, suchas in the case of a fluid sample that is translucent, opaque, or solid.The use of trans-reflectance designs may be especially beneficial incertain embodiments because differential measurement techniques removethe path length dependence of light propagation across microfluidicchannels 16 a-k. Alternatively, both NMR 20 and optical apparatus 22 maymeasure the same or substantially the same fluid volume, as illustratedin FIGS. 2A and 2B. FIGS. 2A and 2B are illustrative in nature, as thoseordinarily skilled in the art will realize a variety of other opticaldesigns may also be utilized. Note that some optical techniques are morephase sensitive, such as florescent techniques, which are more sensitivefor the gas phase. This can isolate, for example, gas composition in agas/liquid mixture. Absorbance is more sensitive to liquid volumes.

As previously described, compositional analysis apparatus 22 may also bea chromatographic apparatus. FIG. 2C illustrates such an exemplaryembodiment in which a chromatographic column 30 is utilized as amicrofluidic channel 16 a-k. As understood in the art, chromatography isa destructive technique; thus, in certain embodiments, the microfluidicchannel being utilized for such analysis is solely dedicated tochromatography. Here, chromatographic column 30 comprises an inlet andoutlet valve 18 a,b as previously described. However, chromatographiccolumn 30 further comprises an inlet 32 for a mobile phase fluid inwhich to mobilize the fluid sample volume along chromatographic column30 during testing, as will be understood by those ordinarily skilledpersons mentioned herein. Exemplary mobile phase fluids include, forexample, hydrogen or helium for gas chromatography, and differentorganic and inorganic solvents may be utilized for liquidchromatography.

The mobile fluid may be stored in a reservoir located on microfluidicdevice 100. A detector 34 is also positioned along chromatographiccolumn 30 to detect the compositional characteristics and generate andtransmit the corresponding signals to device circuitry 24. Exemplarydetectors include, for example, thermal conductivity detectors, MSdetectors or optical detectors including index of refraction. Duringtesting, valves 18 a, 18 b may be opened whereby the mobile fluid flowsinto chromatographic column 30 via inlet 32, thus moving the fluidsample volume up past detector 34 where measurements are taken. Notethat the phase specific semi-permeability membrane (e.g., gas phasemembrane) can be used to augment analysis of the gas phase in adifferential liberation experiment by gas chromatography. If a flash isperformed, the entire liquid volume may be analyzed by gaschromatography.

After the phase and compositional characteristic data has beentransmitted by NMR apparatus 20 and compositional analysis apparatus 22,respectively, device circuitry 24 may then utilize the data to performan EOS analysis. In addition, device circuitry 24 may combine theresulting EOS data with fluid viscosity data, rock properties includingpermeability and porosity and reservoir geometry to conduct a reservoirsimulation. There are a variety of software platforms available toconduct such analysis, as will be understood by those ordinarily skilledin the art having the benefit of this disclosure.

Now, with reference to FIG. 3, a microfluidic device 300 is illustratedaccording to an alternate exemplary embodiment of the present invention.The fluid inlet/outlets, valves and the parallel arrangement ofmicrofluidic channels 16 a-k are the same as those described in FIG. 1.Thus, FIG. 3 is a simplified version of microfluidic device 100 intendedto illustrate certain inventive aspects, showing a cut-away topside viewsimilar to that of FIG. 2A. Here, a plurality of microfluidic channels16 a-l are positioned in parallel inside of NMR apparatus 20. NMRapparatus 20 comprises a Halbach cylinder that generates a uniformmagnetic field 36 inside the inner hallow space. As will be understoodby those skilled persons mentioned herein, a Halbach array isconstructed using multiple pieces of magnets in pre-arranged directionssuch that the magnetic field generated inside the cylinder is highlyhomogeneous, but the field outside is substantially zero. Eachmicrofluidic channel 16 a-1 includes an individual transmitter andreceiver coil to generate and transmit phase characteristic signals todevice circuitry 24. However, alternatively, a single transceiver mayalso be utilized for performing measurements of all channels.

One advantage of the embodiment of FIG. 3 is that utilization of asingle Halbach magnet provides a homogeneous static field for multiplemicrofluidic channels, which results in a reduction of costs andmanufacturability. Another advantage is that the overall size requiredto implement a plurality of Halbach magnets is very small, thus allowingthe microfluidic device to be utilized in very limited spaces.

In yet another exemplary embodiment, multiple parallel microfluidicchannels may be mounted on a micro-fabricated chip in a planarconfiguration. If, for some reason, other electronic circuit orperipheral parts prohibit the use of a reasonable sized Halbach magnet,a unilateral magnetic field configuration may be utilized. There are avariety of magnet designs which can generate a unilateral magneticfield, as will be understood by those ordinarily skilled in the arthaving the benefit of this disclosure. Moreover, in certain exemplaryembodiments described herein, it is not critical that the unilateralmagnetic field be spatially homogeneous over a prolonged length ofmicrofluidic channels 16 a-k, since each microfluidic channel 16 a-k canbe tuned to the resonance frequency based upon the strength of themagnetic field at its location.

FIG. 4 illustrates a microfluidic device 400 according to yet anotheralternate exemplary embodiment of the present invention. The fluidinlet/outlets, valves and the parallel arrangement of microfluidicchannels 16 a-k are the same as those described in FIG. 1. Like FIG. 3,FIG. 4 is a simplified illustration of microfluidic device 100 intendedto convey certain novel features. NMR apparatus 20 of microfluidicdevice 400 comprises a first magnet 38 a and a second magnet 38 bpositioned adjacent to one another along a common center axis 40.Although not shown, in certain exemplary embodiments, magnets 38 a,b maybe held in placed by a mechanical supporting structure positionedbetween the magnets. Such a supporting structure may be made with, forexample, non-magnetic material such that no interference with the fieldis expected. Alternatively, magnetic material may be used such that thestatic magnetic field can be enhanced at the sensitive volume. Thepolarity of magnet 38 a is opposite the polarity of magnet 38 b in orderto generate a “monopole” magnetic field within the mid-section areasurrounding magnets 38 a,b. Microfluidic channels 16 are arranged inparallel as previously described, and positioned along ring perimeter 42(which has a relatively uniform magnetic field).

Still referring to FIG. 4, in certain exemplary embodiments, one, asubset of, or all of microfluidic channels 16 are positioned atdifferent vertical and lateral distances from the center axis 40 offirst and second magnets 38 a,b in order to provide measurements of thefluid sample volumes at different magnetic field gradients andstrengths. For example, one or more of microfluidic channels 16 may belaterally positioned further from center axis 40 than other microfluidicchannels 16. Alternatively, one or more of the channels may bepositioned at different vertical positions relative to one another. Insuch embodiments, when microfluidic channels 16 are filled with the samefluids, measurements at different gradient strengths provide diffusivitymeasurements, while measurements at different field strengths provideNMR frequency dispersion measurements.

Although not illustrated, microfluidic devices 100,300,400 may bedeployed downhole utilizing a variety of methodologies such as, forexample, in conjunction with MWD or LWD operations. In an exemplaryembodiment of the present invention, microfluidic devices 100, 300, 400comprise a part of formation testing tool deployed via a wireline whichprovides for electrical coupling and bi-directional data communication.The formation testing tool may also include, for example, modules tohandle electrical/hydraulic power conversion, fluid sample storage, datarecordation, flow control, telemetry, etc., as would be readilyunderstood by persons ordinarily skilled in the art having the benefitof this disclosure. Moreover, microfluidic devices 100,300,400 mayfurther include an on-board CPU to monitor and control operation ofmicrofluidic devices 100,300,400 during PVT analysis operations, or asurface control unit could be utilized to accomplish the same, or somecombination of the two.

Operation of the present invention will now be described with referenceto method 500 of FIG. 5. During operation of certain exemplaryembodiments of the present invention, one or more microfluidic devices100,300,400 are deployed at block 502 to perform a PVT analysis ofwellbore fluid. Such deployment may be, for example, as part of awireline assembly, logging assembly (logging while drilling or measuredwhile drilling formation test, for example), surface assembly (mudshack, for example), or a drilling assembly (as part of the bit, forexample). There would be various methods by which to implement suchembodiments, as would be understood by those ordinarily skilled in theart having the benefit of this disclosure. Furthermore, those sameskilled persons will realize the microfluidic devices may be deployeddownhole as a stand-alone unit or as otherwise desired. Once deployed tothe desired position, wellbore fluid is provided to the microfluidicdevice where it is received by inlet port 12 (FIG. 1). At block 504,fluid sample volumes are then communicated to a plurality of parallelmicrofluidic channels using various pumps and valves as previouslydescribed. For example with reference to FIG. 1, valves 18 a are openedwhile valves 18 b remain closed, thus allowing each microfluidic channel16 a-k to fill to any desired volume.

At block 506, a desired pressure and temperature is applied to the fluidsample volumes in each microfluidic channel. As will be understood bythose ordinarily skilled in the art having the benefit of thisdisclosure, the pressure and/or temperature of the microfluidic channelsmay be applied and/or altered in a variety of ways, including thosedescribed herein. Once the pressure and/or temperature of the fluidsample volume is altered, the PVT analysis described herein may berepeated.

At block 508, an NMR apparatus is then utilized to apply a magneticfield across the microfluidic channels. In certain methodologies inwhich the volume of each fluid sample volume is not known, aone-dimensional NMR profile may be acquired from which the volume can bedetermined. In other embodiments in which the volume of each fluidsample volume is known, signal amplitude, relaxation and/or diffusioncan be monitored to provide fluid discrimination. Additionally, themagnetic field may be generated using a variety of magnetic designs,such as, for example, a single Halbach magnetic cylinder surrounding themicrofluidic channels or any of the other designs described herein.Moreover, a homogeneous magnetic field may be applied across one, asubset of, or each microfluidic channel. Alternatively, a gradientmagnetic field may be applied across one, a subset of, or eachmicrofluidic channel.

At block 510, utilizing the NMR apparatus, a plurality of first signalscorresponding to phase characteristics of each fluid sample volume aregenerated. In certain exemplary embodiments, the first signals aregenerated simultaneously, while in others the signals are generatedsequentially. This will provide relative or total phase (gas, liquid,solid) volume measurements per microfluidic channel, which will bedependent upon the pressure or temperature applied to it. As previouslydescribed, the temperature and/or pressure of the fluid sample volumesmay be altered, and the first signals generated again to perform as manyPVT experiments as desired. Thus, for example, the same or differentpressure, volume or temperature may be applied to the fluid samplevolumes as desired.

At block 512, a PVT analysis is then performed based upon the firstsignals utilizing processing circuitry. Here, in certain embodiments,the phase characteristic data of each channel embodied in the firstsignals is combined statistically for a complete PVT analysis, thusimproving the accuracy over the repeated experiments occurring in thechannels. Unlike conventional approaches which utilize a single fluidvolume, the present invention takes advantage of the parallel channelsand small fluid volumes within those channels to rapidly performmultiple PVT experiments simultaneously. For example, the volume andtemperature of a channel may be changed over a limited range.Alternatively, different pressure, temperature and volume measurementsmay be performed in each channel. The different pressure, temperature,and volume measurements are then combined to form an experiment such as,for example, Differential Liberation, Constant Composition, or ConstantVolume Depletion. There are also other special PVT analysis including,for example, flow assurance testing, fluid compatibility etc. PVTexperiments are performed for the purpose of determining fluidproperties (e.g., bulk properties) and fluid behavior (e.g., phasebehavior or fluid compatibility).

Thereafter, a statistical average is taken of the resulting phase datato ensure accuracy. One exemplary measurement is the amount of phase ata pressure, volume, temperature point in PVT space with the goal ofmapping out the fluid response for the PVT space. For example, in onechannel, the gas/liquid split may be determined as 50/50 volume %. Inanother it might be 49/51, in a third it might be 49/51, in a fourth itmight be 48/52. Therefore, according to is distribution statistics, thevolume split is most likely 49/51. The standard deviation on thatmeasurement is +/−0.8165. Distribution statistics can provide thefurther statistical description including, for example, confidence ofthe measurement. Any variety of PVT experiments may be performedutilizing the first signals, such as, for example, phase behavior,transport property or bulk property experiments. As previouslymentioned, methodology 500 may be utilized to analyze wellbore fluid.Additionally, in certain methodologies, the PVT analysis is performedwhile microfluidic device 100,300,400 is downhole.

The exemplary methodologies described herein may be utilized to performany variety of PVT experiments. For example, substantially identicalpressures and temperatures may be applied to two or more fluid samplevolumes. Alternatively, different pressures and temperatures may beapplied to two or more fluid sample volumes. Accordingly, the presentinvention provides experimental repeatability which greatly reduces thetime required for a PVT analysis as compared to conventional approaches.For example, if an experiment was intended to determine the bubble pointtemperature for reservoir fluid at 3K psi, fifteen microfluidic channelsmay filled with the same volume of reservoir fluid. Five microfluidicchannels are heated to 350 F, five are heated to 360 F, and five areheated to 370 F. The NMR apparatus then generates the phasecharacteristic signals as described herein, which are ultimatelyutilized to determine the bubble point temperature for the wellborefluid at 3K psi. Certain embodiments may also utilize redundantmeasurements or statistical analysis of the signals to increase accuracyacross multiple experiments. Ultimately, any number of microfluidicchannels with different pressures, volumes or temperatures may beanalyzed for any variety of PVT experiments within or between chips.

FIG. 6 illustrates another methodology 600 to perform a PVT analysis, inaccordance to certain exemplary methods of the present invention. Atblock 602, the microfluidic device 100, 300, 400 generates one or moresecond signals corresponding to a compositional characteristic of thefluid sample volume utilizing a compositional analysis apparatus(chromatographic, optical or NMR apparatus, for example). Althoughillustrated as occurring after block 512, block 602 may occur before orconcurrent with any of blocks 504-512. In one embodiment, certainmicrofluidic channels, and their corresponding second signals,correspond to different compositional characteristics of the fluidsample. Nevertheless, at block 604, the first and second signals may beutilized to perform an EOS analysis. At block 606, the equation of stateanalysis may then be utilized to perform a reservoir simulation of thefluid sample.

Accordingly, exemplary embodiments of the present invention describedherein make use of microfluidic processes to parallelize the PVTanalysis such that part of a pressure, temperature, volume combinationis performed separate from others. The PVT data is then recombinedstatistically for a complete PVT analysis. Utilizing microfluidics asthe enabling technology, the present invention divides laboratorytesting into hundreds, for example, of micro to nano chambers. If, forexample, a full PVT analysis would take a week, then by dividing theexperiment into 200 parallel microfluidic channels using the presentinvention, the experiment could be completed in less than an hour. Thus,a batch process is parallelized for rapid response via fluidicmanipulation, temperature control, pressure control and volume control.Regarding volume, certain embodiments utilize as little as 250micro-liters or less or 2 milli-liters of fluid with only 8 PVTexperimental repeats.

Also, due to the small nature of the microfluidic devices, temperatureand pressure control is augmented. In fact, depending on the size of thedevice, temperature may be rapidly and easily controlled even in adownhole environment utilizing technology such as, for example, thermalelectric cooling or thermal electric heating. Combining the technologywith optical, or micro-NMR sensing capability including, but not limitedto, induction-based or non-induction-based type NMR sensors, then phasebehavior and composition may be directly determined in the fluidic chip.Integration of the microfluidic device with chromatographic technologyon a micro scale and mass spectrometery completes the capability of afull PVT laboratory.

The size of the microfluidic devices also allows for many statisticalrepeats of a PVT experiment, or multiple microfluidic station monitoringthroughout wireline or LWD sampling operations including, but notlimited to, a Pumpout. The size of the microfluidic devices also enablesconvenient location of devices in, or associated with, sampling chambersor surface transfer apparatuses.

Additionally, as previously described, the PVT analysis performed usingthe present invention may relate to phase behavior, transport propertiesor bulk properties of the fluid sample volume. Transport properties mayinclude viscosity or thermal conductivity. Parallel multidivisionalgradient perturbations (temperature, pressure, electric fields) may berealized. Bulk properties may include phase envelope, compressibility,thermal expansion, density, phase transitions (asphaltenes perception,for example), wax appearance, and analytical properties (pour point,cloud point, metals content, cut densities, cut viscosities, etc.).Other PVT analysis may include special tests such as, for example,differential liberation, constant composition, constant volumedepletion, swell tests, fluid compatibility or flow assurance. Otherfluids may be injected into the microfluidic channels for mixing withthe fluid sample volume to perform fluid compatibility tests. Physicaland chemical properties of refinery separations, sulfur content(speciation) and ash content may also be analyzed.

Accordingly, the microfluidic devices of the present invention provide anumber of advantages. First, for example, conventional laboratoryanalysis may be enhanced due to the rapid nature and lower samplerequirements of the present invention. Second, the microfluidic devicesof the present invention are easily adaptable between well site andlaboratory settings. Third, the present invention provides efficientautomation in a laboratory, process control, well site or subseaenvironment. For example, to control a process, measurements are oftenmade to ensure the process is under control. Adjustments to the processmay be controlled by a feedback loop automatically with computeralgorithms providing the control based on these measurements. Fourth,full rapid chemical analysis in a formation testing environment isprovided by the present invention.

Embodiments described herein further relate to any one or more of thefollowing paragraphs:

1. A method to perform a pressure-volume-temperature (“PVT”) analysis ofwellbore fluid using a microfluidic device, the method comprising:receiving a wellbore fluid sample into an inlet port of a microfluidicdevice; communicating a volume of the wellbore fluid sample to aplurality of microfluidic channels; applying pressure and temperature toeach fluid sample volume; applying a magnetic field across themicrofluidic channels using a nuclear magnetic resonance (“NMR”)apparatus; generating first signals corresponding to phasecharacteristics of each fluid sample volume within the microfluidicchannels using the NMR apparatus, the phase characteristics of eachfluid sample volume being dependent upon the pressure or temperatureapplied to the fluid sample volume; and performing a PVT analysis basedupon the first signals using the processing circuitry.

2. A method as defined in paragraph 1, wherein generating the firstsignals further comprises utilizing a one-dimensional NMR profile todetermine the fluid sample volumes.

3. A method as defined in paragraphs 1 or 2, wherein generating thefirst signals further comprises determining a diffusion of the fluidsample volumes.

4. A method as defined in any of paragraphs 1-3, wherein performing thePVT analysis further comprises performing a statistical analysis of thefirst signals.

5. A method as defined in any of paragraphs 1-4, wherein performing thePVT analysis further comprises determining at least one of a phasebehavior, transport property or bulk property of the fluid samplevolumes.

6. A method as defined in any of paragraphs 1-5, further comprisingutilizing a compositional analysis apparatus to generate a second signalcorresponding to a compositional characteristic of the fluid samplevolume present within at least one of the microfluidic channels.

7. A method as defined in paragraph 6, further comprising performing anequation of state analysis based upon the first and second signals usingthe processing circuitry.

8. A method as defined in paragraph 7, further comprising utilizing theequation of state analysis to perform a reservoir simulation of thefluid sample.

9. A method as defined in any of paragraphs 6-8, wherein the secondsignals of each microfluidic channel correspond to a differentcompositional characteristic of the fluid sample volume.

10. A method as defined in paragraph 6, wherein the compositionalanalysis apparatus comprises at least one of a chromatographic, optical,or NMR apparatus.

11. A method as defined in paragraph 10, wherein the optical apparatuscomprises an Integrated Computational Element.

12. A method as defined in any of paragraphs 1-11, wherein the magneticfield is generated using a single Halbach magnetic cylinder surroundingthe microfluidic channels.

13. A method as defined in any of paragraphs 1-12, wherein the magneticfield is generated using an NMR apparatus comprising: a first and secondmagnet positioned adjacent to one another along a common axis such thata polarity of the first magnet is opposite a polarity of the secondmagnet, thereby generating a monopole field between the first and secondmagnets; and a perimeter surrounding the first and second magnets alongwhich the microfluidic is channels are positioned, the perimeter havinga substantially uniform magnetic field.

14. A method as defined in paragraph 13, further comprising positioningthe microfluidic channels at different vertical and lateral distancesfrom the monopole field.

15. A method as defined in any of paragraphs 1-14, wherein the phasecharacteristic is an amount of a solid, gas or liquid present within thefluid sample volume.

16. A method as defined in any of paragraphs 1-15, further comprisingaltering the temperature or pressure of the fluid sample volumes.

17. A method as defined in any of paragraphs 1-16, wherein applyingpressure and temperature to each fluid sample volume further comprises:applying substantially identical pressures and temperatures to two ormore fluid sample volumes; or applying different pressures andtemperatures to two or more fluid sample volumes.

18. A method as defined in any of paragraphs 1-17, further comprising atleast one of: deploying the device as part of a wireline assembly;deploying the device as part of a logging assembly; deploying the deviceas part of a surface assembly; or deploying the device as part of adrilling assembly.

19. A method as defined in any of paragraphs 1-18, wherein the PVTanalysis is performed while the device is downhole.

20. A method as defined in any of paragraphs 1-19, wherein the magneticfield comprises: a homogeneous magnetic field applied across one, asubset of, or each microfluidic channel; or a gradient magnetic fieldapplied across one, a subset of, or each microfluidic channel.

21. A microfluidic device for performing a pressure-volume-temperature(“PVT”) analysis of wellbore fluid, the device comprising: an inlet portto receive a wellbore fluid sample; a plurality of microfluidic channelsin fluid communication with the inlet port to thereby receive a volumeof the wellbore fluid sample and to apply a pressure and temperature toeach fluid sample volume; a nuclear magnetic resonance (“NMR”) apparatuspositioned adjacent the microfluidic channels to generate a magneticfield across the microfluidic channels, to thereby generate firstsignals corresponding to phase characteristics of each fluid samplevolume within the microfluidic channels, the phase characteristics ofeach fluid sample volume being dependent is upon the pressure andtemperature applied to the fluid sample volume; and processing circuitrycommunicably coupled to the NMR apparatus to perform a PVT analysisbased upon the first signals.

22. A device as defined in paragraph 21, further comprising acompositional analysis apparatus positioned adjacent to at least one ofthe microfluidic channels to generate a second signal corresponding to acompositional characteristic of the fluid sample volume present withinthe microfluidic channel.

23. A device as defined in paragraph 22, wherein the processingcircuitry is further adapted to perform an equation of state analysisbased upon the first and second signals.

24. A device as defined in paragraphs 22 or 23, wherein the secondsignals generated by each microfluidic channel correspond to a differentcompositional characteristic of the fluid sample volume.

25. A device as defined in any of paragraphs 22-24, wherein thecompositional analysis apparatus comprises at least one of achromatographic, optical or NMR apparatus.

26. A device as defined in paragraph 25, wherein the optical apparatuscomprises an Integrated Computational Element.

27. A device as defined in paragraphs 25 or 26, wherein thechromatographic apparatus comprises a dedicated microfluidic channel.

28. A device as defined in any of paragraphs 21-27, wherein: the NMRapparatus comprises a single Halbach magnetic cylinder surrounding themicrofluidic channels; and each microfluidic channel comprises atransmitter and receiver coil.

29. A device as defined in any of paragraphs 21-27, wherein the NMRapparatus comprises: a first and second magnet positioned adjacent toone another along a common axis such that a polarity of the first magnetis opposite a polarity of the second magnet, thereby generating amonopole field between the first and second magnets; and a perimetersurrounding the first and second magnets along which the microfluidicchannels are positioned, the perimeter having a substantially uniformmagnetic field.

30. A device as defined in paragraph 29, wherein the microfluidicchannels are positioned at different vertical and lateral distances fromthe first and second magnets.

31. A device as defined in any of paragraphs 21-30, wherein the phasecharacteristic is is an amount of a solid, gas or liquid present withinthe fluid sample volume.

32. A device as defined in any of paragraphs 21-31, further comprising athermal electric cooling device or thermal electric heating devicepositioned adjacent to the microfluidic channels to alter thetemperature of the fluid sample volumes.

33. A device as defined in any of paragraphs 21-32, wherein the PVTanalysis determines at least one of a phase behavior, transport propertyor bulk property of the fluid sample volumes.

34. A device as defined in any of paragraphs 21-33, wherein the deviceforms part of a drilling assembly, wireline assembly, logging assembly,or surface assembly.

35. A device as defined in any of paragraphs 21-34, wherein the magneticfield comprises: a homogeneous magnetic field applied across one, asubset of, or each microfluidic channel; or a gradient magnetic fieldapplied across one, a subset of, or each microfluidic channel.

36. A method to perform a pressure-volume-temperature (“PVT”) analysisusing a microfluidic device, the method comprising: receiving a volumeof a fluid sample into a plurality of microfluidic channels; applyingpressure and temperature to each fluid sample volume; generating, inparallel, first signals corresponding to phase characteristics of eachfluid sample volume within the microfluidic channels, the phasecharacteristics of each fluid sample volume being dependent upon thepressure or temperature applied to the fluid sample volume; andperforming a PVT analysis based upon the first signals.

37. A method as defined in paragraph 36, wherein the first signals aregenerating using a nuclear magnetic resonance apparatus.

38. A method as defined in paragraphs 36 or 37, further comprisinggenerating one or more second signals corresponding to a compositionalcharacteristic of the fluid sample volumes present within themicrofluidic channels.

39. A method as defined in paragraph 38, further comprising performingan equation of state analysis based upon the first and second signals.

40. A method as defined in paragraph 39, further comprising performing areservoir simulation based upon the equation of state analysis.

Although various embodiments and methodologies have been shown anddescribed, the is invention is not limited to such embodiments andmethodologies and will be understood to include all modifications andvariations as would be apparent to one skilled in the art. Therefore, itshould be understood that the invention is not intended to be limited tothe particular forms disclosed. Rather, the intention is to cover allmodifications, equivalents and alternatives falling within the spiritand scope of the invention as defined by the appended claims.

What is claimed is:
 1. A method to perform a pressure-volume-temperature(“PVT”) analysis of wellbore fluid, the method comprising: receiving awellbore fluid sample into an inlet port of a PVT device; separating thefluid sample by communicating a volume of the fluid sample to one ormore of a plurality of channels within the PVT device, wherein ananalysis apparatus is positioned adjacent the channels and a pressure ortemperature of at least one fluid sample volume within the channels isaltered such that a pressure and temperature combination of at least onefluid sample volume is different from that of at least one other fluidsample volume within the plurality of channels, thus altering a phase ofat least one of the fluid sample volumes within the channels;interacting the analysis apparatus with the fluid sample volume in thechannels to perform a gas chromatography technique and mass spectrometrytechnique on the fluid sample volume; in response to the interaction,using the analysis apparatus to generate one or more signalscorresponding to characteristics of the fluid sample volume; and usingprocessing circuitry, performing a PVT analysis based upon the signals.2. The method as defined in claim 1, wherein the PVT device controls oralters a temperature or pressure of the fluid sample prior tointeraction with the analysis apparatus.
 3. The method as defined inclaim 2, wherein the PVT device at least partially changes a phase ofthe fluid sample.
 4. The method as defined in claim 3, wherein: the PVTdevice changes the fluid sample to a gas state; or the change includes aprecipitation of asphaltenes.
 5. The method as defined in claim 4,wherein a semi-permeable membrane or gas membrane extracts the gas stateof the fluid sample.
 6. The method as defined in claim 1, wherein theanalysis apparatus measures at least one of an inorganic gas, CO₂, H₂S,organic gas, methane (C1), ethane (C2), propane (C3), water, ordissolved ions.
 7. The method as defined in claim 1, wherein hydrogen orhelium is introduced at an inlet of the one or more channels as a mobilefluid.
 8. The method as defined in claim 1, wherein the one or moresignals are generated by a thermal conductivity detector or opticaldetector.
 9. The method as defined in claim 1, wherein the massspectrometry technique is achieved using a Fourier transform ioncyclotron resonance mass spectrometry.
 10. The method as defined inclaim 1, wherein the analysis apparatus interacts with the fluid samplevolume to perform the gas chromatography and mass spectrometrytechniques along one channel.
 11. The method as defined in claim 1,wherein the analysis apparatus interacts with the fluid sample volume toperform the gas chromatography technique along a first channel and themass spectrometry technique along a second channel.
 12. The method asdefined in claim 1, wherein the analysis apparatus interacts with thefluid sample volume to perform the gas chromatography technique and themass spectrometry technique along multiple channels in parallel.
 13. Themethod as defined in claim 1, wherein: the plurality of channels includean inlet and outlet; the outlets of the plurality of channels are influid communication with a sampling chamber of the PVT device; and theoutlets separate the plurality of channels from the sampling chamber.14. The method as defined in claim 1, wherein performing the PVTanalysis further comprises performing a statistical analysis of the oneor more signals.
 15. The method as defined in claim 1, furthercomprising recombining a signal of the one or more channels to determinethe characteristics of the fluid sample volume.
 16. The method asdefined in claim 1, wherein at least two channels of the plurality ofchannels are optimized to determine different characteristics inparallel.
 17. The method as defined in claim 1, wherein performing thePVT analysis further comprises determining at least one of a phasebehavior, transport property or bulk property of the fluid samplevolumes.
 18. The method as defined in claim 1, further comprisingperforming an equation of state analysis based upon the one or moresignals using the processing circuitry.
 19. The method as defined inclaim 18, further comprising utilizing the equation of state analysis toperform a reservoir simulation of the fluid sample volume.
 20. Themethod as defined in claim 1, wherein the one or more signals of eachchannel correspond to a different characteristic of the fluid samplevolume.
 21. The method as defined in claim 1, further comprising atleast one of: deploying the PVT device as part of a wireline assembly;deploying the PVT device as part of a logging assembly; deploying thePVT device as part of a surface assembly; or deploying the PVT device aspart of a drilling assembly.
 22. The method as defined in claim 1,wherein the PVT analysis is performed while the PVT device is downhole.23. The method as defined in claim 1, wherein the PVT analysis is acompositional PVT analysis.
 24. A device for performing apressure-volume-temperature (“PVT”) analysis of wellbore fluid, thedevice comprising: an inlet port to receive a wellbore fluid sample; aplurality of channels in fluid communication with the inlet port tothereby receive a volume of the wellbore fluid sample; an analysisapparatus positioned adjacent the channels to interact with the fluidsample volume in the channels to alter a pressure or temperature of atleast one fluid sample volume within the channels such that a pressureand temperature combination of at least one fluid sample volume isdifferent from that of at least one other fluid sample volume within theplurality of channels and to perform a gas chromatography technique andmass spectrometry technique on the fluid sample volume, to therebygenerate signals corresponding to characteristics of each fluid samplevolume within the channels, wherein a phase of at least one of the fluidsample volumes within the channels is altered; and processing circuitrycommunicably coupled to the analysis apparatus to perform a PVT analysisusing the signals.
 25. The device as defined in claim 24, furthercomprising a semi-permeable membrane to extract a gas phase of the fluidsample volume.
 26. The device as defined in claim 24, wherein theanalysis apparatus is positioned to interact with the fluid samplevolume to perform the gas chromatography and mass spectrometrytechniques along one channel.
 27. The device as defined in claim 24,wherein the analysis apparatus is positioned to interact with the fluidsample volume to perform the gas chromatography technique along a firstchannel and the mass spectrometry technique along a second channel. 28.The device as defined in claim 24, wherein the analysis apparatus ispositioned to interact with the fluid sample volume to perform the gaschromatography technique and the mass spectrometry technique alongmultiple channels in parallel.
 29. The device as defined in claim 24,wherein: the plurality of channels include an inlet and outlet; theoutlets of the plurality of channels are in fluid communication with asampling chamber of the device; and the outlets separate the pluralityof channels from the sampling chamber.
 30. The device as defined inclaim 24, wherein the processing circuitry is further adapted to performan equation of state analysis based upon the signals.
 31. The device asdefined in claim 24, wherein the signals generated for each channelcorresponds to a different characteristic of the fluid sample volume.32. The device as defined in claim 24, further comprising a thermalelectric cooling device or thermal electric heating device positionedadjacent to the channels to control or alter the temperature of at leastpart of the device.
 33. The device as defined in claim 24, wherein thedevice forms part of a drilling assembly, wireline assembly, loggingassembly, or surface assembly.
 34. The device as defined in claim 24,wherein the device is a compositional PVT analysis device.